why is that the church do not allow some early father’s writings on the bible?
because Jesus’ apostles wrote them and they were immediate successors. The Bible concluded its writings upon the death of the apostle John. He was the last remaining witness to Christ. Early Church Fathers I don’t believe have any physical witness to Christ as did the apostles and St. Paul. Correct me if I am wrong on that.
I am not sure what you mean by not allowing early father’s writings of the Bible. All are available from Clement of Alexandria etc. to all the recognized Fathers of that time.
I think you must mean the Gnostic Gospels and writings which were forbidden by the Church in the 2nd and 3rd centuries while the Church was establishing the Canon.
A lot of the Dan Browns, Holy Blood Holy Grail authors, Elaine Pagels and sensationalists propagate these heretical texts to sell books, movies, what have you. They were not accepted into the Canon because unlike our 4 Gospels and Apostles’ and Disciples’ letters, they were a mishmash of every mystical sect then running in the Middle East, some preaching the teachings of one Manes (who taught that there were 2 equal gods, one good, one bad), some preaching that the physical world was all Evil and the Earth was created by an evil force, and most preaching the false gospel that one could attain salvation not through Jesus but from learning secret, esoteric teachings said to be of Jesus - Gnosticism.
Most of these texts were not written until the 3rd Century, way after the eyewitnesses who compiled our Bible died.